add some more helpful paranoia to disposeOnce.
add some more helpful paranoia to disposeOnce.

Change-Id: I46f2bf5115f2b80990fdcac75bd31615c4221b9e

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core